docs: def display_drilldown_as_ul(category, using='categories.Category'):
      """
      Render the category with ancestors and children using the
      ``categories/ul_tree.html`` template.
  
      Example::
  
          {% display_drilldown_as_ul "/Grandparent/Parent" %}
  
      or ::
  
          {% display_drilldown_as_ul category_obj %}
  
      Returns::
  
          <ul>
            <li><a href="/categories/">Top</a>
            <ul>
              <li><a href="/categories/grandparent/">Grandparent</a>
              <ul>
                <li><a href="/categories/grandparent/parent/">Parent</a>
                <ul>
                  <li><a href="/categories/grandparent/parent/child1">Child1</a></li>
                  <li><a href="/categories/grandparent/parent/child2">Child2</a></li>
                  <li><a href="/categories/grandparent/parent/child3">Child3</a></li>
                </ul>
                </li>
              </ul>
              </li>
            </ul>
            </li>
          </ul>
      """
      cat = get_category(category, using)
      if cat is None:
          return {'category': cat, 'path': []}
      else:
          return {'category': cat, 'path': drilldown_tree_for_node(cat)}